Here are the common signs of chromic dehydration:

Fatigue. Water is the most important source of energy in the body. Dehydration causes the enzymatic activity in the body to slow down, producing tiredness and fatigue. Thus, one of the earliest signs of chronic dehydration is fatigue.
Constipation. The colon is one of the first places the body pulls water when it is short of water in order to provide fluids for other critical functions in the body. Without adequate water, wastes move through the large intestines much more slowly. In fact, sometimes they don’t move at all. Thus, constipation is almost always one of the primary symptoms of chronic dehydration.
High blood pressure. The blood is normally about 94 percent water when the body is fully hydrated. When dehydrated, the blood is thicker causing resistance to blood flow, which thus can raise blood pressure.